body {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
  }
  .calculator {
    background: rgba(78, 78, 82, 0.5);
    border-radius: 10px;
    padding: 20px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
  }
  .display {
    font-size: 2em;
    padding: 10px;
    background-color: #22242980; /* 50% 半透明 */
    text-align: right;
    color: #e8e9e9;
    border-radius: 5px;
    margin-bottom: 10px;
  }
  .keys {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    grid-gap: 10px;
  }
  button {
    padding: 10px;
    font-size: 1.2em;
    border: none;
    border-radius: 5px;
    background-color: #7a7a7d;
    color: #ffffff;
    cursor: pointer;
    transition: background-color 0.3s;
  }
  button:hover {
    background-color: #d0d0d0;
  }
 
  button.option {
    background: #ff9727;
  }